# HW18-1 - ~ E2) where ~ is the mean logarithmic energy lost...

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PROBLEMS 1. In a liquid metal fast breeder reactor, no neutron moderation is desired and sodium is used as a coolant to minimize fission-neutron thermalization. How many scatters with sodium, on the average, would it take for 2-MeV neutrons to reach an average thermal energy of 0.025 eV? ffiNT: review Section 6.5.1. Solution: From Eq. (6.30) the average number of scatters n needed to reduce a neutron's kinetic energy from El to E2 is n = ! In ( !Jl 'I
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Unformatted text preview: ~ E2) where ~ is the mean logarithmic energy lost by a neutron in an elastic scatter with a nucleus of atomic mass number A, namely a f. = 1 + :;--:-lna with a == ~-=-!2: (A + 1)2 u For sodium (A = 23), we find a = 0.8403 and f. = 0.08448. Then the number of elastic scatters with carbon required to reduce a neutron's energy from 2 MeV to 0.025 eV is 1 ( El ) 1 ( 2 X 106 ) n = ~ In "E; = 0.08448 In 0.025 = 215. July 24, 2002...
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## This note was uploaded on 02/01/2010 for the course ECE 4130 taught by Professor Cady during the Spring '06 term at Cornell University (Engineering School).

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